GAS EXCHANGECardio Respiratory
System
GAS EXCHANGE
1. supplies oxygen for aerobic cellular respiration (reactant)
2. removes carbon dioxide from aerobic cellular respiration (product)
3. Must carry out ventilation - actively moving air in and out of body surfaces
4. Terrestrial – gases in air Aquatic – gases dissolved in water
Fig. 42-2
Circularcanal
Radial canalMouth
(a) The moon jelly Aurelia, a cnidarian The planarian Dugesia, aflatworm
(b)
MouthPharynx
2 mm5 cm
SOME AQUATIC INVERTEBRATES: Thin-wall - Gases diffuse through the membrane
Fig. 42-21
Parapodium (functions as gill)(a) Marine worm
Gills
(b) Crayfish (c) Sea star
Tube foot
Coelom
Gills
OTHER AQUATIC INVERTIEBRATES USE GILLS
Fig. 42-23
Air sacs
Tracheae
Externalopening
Bodycell
AirsacTracheole
Tracheoles Mitochondria Muscle fiber
2.5 µmBody wall
Trachea
Air
Arachnids (Spiders/Scorpians) - Book Lungs
Fig. 42-22
Anatomy of gills
Gillarch
Waterflow Operculum
Gillarch
Gill filamentorganization
Bloodvessels
Oxygen-poor blood
Oxygen-rich blood
Fluid flowthrough
gill filament
Lamella
Blood flow throughcapillaries in lamella
Water flowbetweenlamellae
Countercurrent exchange
PO2 (mm Hg) in water
PO2 (mm Hg) in blood
Net diffu-sion of O2
from waterto blood
150 120 90 60 30
110 80 20Gill filaments
50140
GILLS
Fig. 42-UN4
GAS EXCHANGE THROUGH SKIN ONLY SKIN LUNGS
SKIN ONLY
SNAKE RESPIRATORY
REPTILES
DINOSAUR BIRD BONES
Fig. 42-26
Anteriorair sacs
Posteriorair sacs Lungs
Air
Lungs
Air
1 mm
Trachea
Air tubes(parabronchi)in lung
EXHALATIONAir sacs empty; lungs fill
INHALATIONAir sacs fill
LUNGS
Fig. 42-25
Lung
Diaphragm
Airinhaled
Rib cageexpands asrib musclescontract
Rib cage getssmaller asrib musclesrelax
Airexhaled
EXHALATIONDiaphragm relaxes
(moves up)
INHALATIONDiaphragm contracts
(moves down)
Air Volume
Fig. 42-27
Breathingcontrolcenters
Cerebrospinalfluid
Pons
Medullaoblongata
Carotidarteries
Aorta
DiaphragmRib muscles
Fig. 42-UN2Inhaled air Exhaled air
Alveolarepithelial cells
Alveolar spaces
CO2 O2
CO 2 O2
Alveolarcapillaries of
lung
Pulmonary veinsPulmonary arteries
Systemic veins Systemic arteries
Heart
SystemiccapillariesCO
2 O 2
CO2 O2
Body tissue
Fig. 42-28Alveolus
PO2 = 100 mm Hg
PO2 = 40 PO2
= 100
PO2 = 100PO2
= 40
Circulatorysystem
Body tissuePO2
≤ 40 mm Hg PCO2 ≥ 46 mm Hg
Body tissue
PCO2 = 46 PCO2
= 40
PCO2 = 40PCO2
= 46
Circulatorysystem
PCO2 = 40 mm Hg
Alveolus
(b) Carbon dioxide(a) Oxygen
Fig. 42-UN1
Chains
IronHeme
ChainsHemoglobin
HEMOGLOBIN
OXYGEN EXCHANGE
Fig. 42-29a
O2 unloadedto tissuesat rest
O2 unloadedto tissues
during exercise
100
40
0
20
60
80
0 40 80 100
O2 s
atur
ation
of h
emog
lobi
n (%
)
20 60
Tissues duringexercise
Tissuesat rest
Lungs
PO2 (mm Hg)
(a) PO2 and hemoglobin dissociation at pH 7.4
Fig. 42-29b
O2 s
atur
ation
of h
emog
lobi
n (%
)
40
0
20
60
80
0 40 80 10020 60
100
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
pH 7.4pH 7.2
Hemoglobinretains lessO2 at lower pH(higher CO2
concentration)
Fig. 42-UN3
Fetus
Mother
100
80
60
40
20
00 20 40 60 80
O2 s
atur
ation
of
hem
oglo
bin
(%)
100
PO2 (mm Hg)
Fig. 42-30aBody tissue
CO2 produced
CO2 transportfrom tissues
Interstitialfluid CO2
CO2
CO2
Plasmawithin capillary
Capillarywall
H2O
H2CO3
Carbonic acid
Redbloodcell
Hemoglobinpicks up
CO2 and H+Hb
H+HCO3–
Bicarbonate+
HCO3–
To lungs
Fig. 42-30b
HCO3–
HCO3– H++
CO2 transportto lungs
Hemoglobinreleases
CO2 and H+HbH2CO3
H2O
CO2
Plasma withinlung capillary
CO2
CO2
CO2
Alveolar space in lung
CARBON DIOXIDE